Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a first image in a sequence for a display screen or portion thereof with transitional graphical user interface, showing my new design;

FIG. 2 is a front view of a second image thereof;

FIG. 3 is a front view of a third image thereof;

FIG. 4 is a front view of a fourth image thereof; and,

FIG. 5 is a front view of the graphical user interface of FIG. 1 in which a mobile terminal is provided in broken lines to illustrate an example environment.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1 through 4. The subject matter of this patent includes a process or period in which an image changes into another image. This process or period forms no part of the claimed design. The broken line drawing of the mobile terminal, and the text, number, symbol and otherwise images shown in broken lines in the graphical user interface of FIGS. 1 through 5 are for illustrative purposes only and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 